feat: opt-out of events in the app-server (#11319)

Add `optOutNotificationMethods` in the app-server to opt-out events
based on exact method matching

codex-rs/app-server/tests/suite/v2/experimental_api.rs

@@ -30,6 +30,7 @@ async fn mock_experimental_method_requires_experimental_api_capability() -> Resu
             default_client_info(),
             Some(InitializeCapabilities {
                 experimental_api: false,
+                opt_out_notification_methods: None,
             }),
         )
         .await?;
@@ -61,6 +62,7 @@ async fn thread_start_mock_field_requires_experimental_api_capability() -> Resul
             default_client_info(),
             Some(InitializeCapabilities {
                 experimental_api: false,
+                opt_out_notification_methods: None,
             }),
         )
         .await?;
@@ -97,6 +99,7 @@ async fn thread_start_without_dynamic_tools_allows_without_experimental_api_capa
             default_client_info(),
             Some(InitializeCapabilities {
                 experimental_api: false,
+                opt_out_notification_methods: None,
             }),
         )
         .await?;

codex-rs/app-server/tests/suite/v2/initialize.rs

@@ -3,8 +3,12 @@ use app_test_support::McpProcess;
 use app_test_support::create_mock_responses_server_sequence_unchecked;
 use app_test_support::to_response;
 use codex_app_server_protocol::ClientInfo;
+use codex_app_server_protocol::InitializeCapabilities;
 use codex_app_server_protocol::InitializeResponse;
 use codex_app_server_protocol::JSONRPCMessage;
+use codex_app_server_protocol::RequestId;
+use codex_app_server_protocol::ThreadStartParams;
+use codex_app_server_protocol::ThreadStartResponse;
 use pretty_assertions::assert_eq;
 use std::path::Path;
 use tempfile::TempDir;
@@ -108,6 +112,72 @@ async fn initialize_rejects_invalid_client_name() -> Result<()> {
     Ok(())
 }
 
+#[tokio::test]
+async fn initialize_opt_out_notification_methods_filters_notifications() -> Result<()> {
+    let responses = Vec::new();
+    let server = create_mock_responses_server_sequence_unchecked(responses).await;
+    let codex_home = TempDir::new()?;
+    create_config_toml(codex_home.path(), &server.uri(), "never")?;
+    let mut mcp = McpProcess::new(codex_home.path()).await?;
+
+    let message = timeout(
+        DEFAULT_READ_TIMEOUT,
+        mcp.initialize_with_capabilities(
+            ClientInfo {
+                name: "codex_vscode".to_string(),
+                title: Some("Codex VS Code Extension".to_string()),
+                version: "0.1.0".to_string(),
+            },
+            Some(InitializeCapabilities {
+                experimental_api: true,
+                opt_out_notification_methods: Some(vec![
+                    "thread/started".to_string(),
+                    "codex/event/session_configured".to_string(),
+                ]),
+            }),
+        ),
+    )
+    .await??;
+    let JSONRPCMessage::Response(_) = message else {
+        anyhow::bail!("expected initialize response, got {message:?}");
+    };
+
+    let request_id = mcp
+        .send_thread_start_request(ThreadStartParams::default())
+        .await?;
+    let response = timeout(DEFAULT_READ_TIMEOUT, async {
+        loop {
+            let message = mcp.read_next_message().await?;
+            match message {
+                JSONRPCMessage::Response(response)
+                    if response.id == RequestId::Integer(request_id) =>
+                {
+                    return Ok(response);
+                }
+                JSONRPCMessage::Notification(notification)
+                    if notification.method == "thread/started" =>
+                {
+                    anyhow::bail!("thread/started should be filtered by optOutNotificationMethods");
+                }
+                _ => {}
+            }
+        }
+    })
+    .await??;
+    let _: ThreadStartResponse = to_response(response)?;
+
+    let thread_started = timeout(
+        std::time::Duration::from_millis(500),
+        mcp.read_stream_until_notification_message("thread/started"),
+    )
+    .await;
+    assert!(
+        thread_started.is_err(),
+        "thread/started should be filtered by optOutNotificationMethods"
+    );
+    Ok(())
+}
+
 // Helper to create a config.toml pointing at the mock model server.
 fn create_config_toml(
     codex_home: &Path,